When the teeth in a patient's mouth are displaced from an even or uniform disposition, such displacements tend to produce problems over an extended period of time. For example, such displacements may produce problems in the patient's gums. These problems may cause the retention of teeth by the patient's gums to become weakened so that the teeth become loose in the patient's mouth. The problem may become so aggravated that the teeth may eventually have to be removed from the patient's mouth.
To prevent the conditions in a patient's mouth from deteriorating, orthodontists often attempt to reset the positions of the teeth in the patient's mouth. The orthodontists do this by attaching braces to the patient's teeth and by gradually adjusting the forces applied by the braces to the teeth. These forces act against the teeth in the patient's mouth to move the teeth gradually toward the positions desired by the orthodontist.
The braces are generally formed by brackets and an arch wire supported in a slot or groove in each of the brackets. Each bracket is adhered to an individual tooth by a pad forming a part of the bracket. The arch wire extends between the brackets on adjacent teeth and applies a force to the teeth to move the teeth toward the positions determined by the patient's orthodontist. Until now, the grooves on the different brackets have been substantially uniform. Because of this, the forces of the arch wire on the teeth have had to be adjusted by bending or otherwise distorting the wires.
The techniques discussed in the previous paragraph have had some beneficial effect. However, they are expensive and imperfect. One reason is that they require a considerable amount of work by the orthodontist to adjust progressively the forces applied against the teeth. Another reason is that the bending and distortion of the arch wire to adjust the forces on the different teeth have been empirical or intuitive on the part of the orthodontist and have been based in large part upon the experience of the orthodontist. As will be appreciated, even an experienced orthodontist is not able to bend or twist an arch wire precisely so that the proper force will be produced on the brackets attached to the individual teeth.
It has been appreciated in the art that it would be desirable to construct the brackets so that the arch wire is planar in an elevational view and is progressively curved in a plan view even after attachment to the brackets and after the disposition in the patient's mouth of the brace formed by the brackets and the arch wire. For example, such a brace has been proposed in U.S. Pat. No. 3,477,128 issued to Lawrence F. Andrews on Nov. 11, 1969 and U.S. Pat. No. 3,660,900 issued to Lawrence F. Andrews on May 9, 1972.
The proposals made by Andrews are based upon measurements made in a few skulls. They are not made on an individual basis for each patient. Furthermore, the proposals made by Andrews involve only a limited number of parameters. These parameters are mostly confined to individual characteristics of the grooves in the brackets. As will be appreciated, the proposals made by Andrews are quite crude and would not be sufficient to provide, for the individual parameters represented by the unique configuration and disposition of the teeth in each patient's mouth, a brace in which the arch wire is planar in an elevational view and is progressively curved in a plan view. U.S. Pat. No. 5,011,405 issued on Apr. 30, 1991, to Marc S. Lemchen for a "Method of Determining Orthodontic Bracket Placement" and assigned of record to Dolphin Imaging Systems is also pertinent with respect to methods of positioning brackets on an arch wire to dispose a patient's teeth in optimal positions in the patient's mouth.
The Andrews patents are now twenty years old (in one case), or almost twenty years old (in the other case). In that period of time, no one has been able to advance the state of the art beyond the crude state proposed by Andrews. As a practical matter, no one has been able to dispose an arch wire on the slots in brackets on a patient's teeth so that the arch wire is planar in an elevational view and is progressively curved in a planar view and so that the arch wire will adjust the positioning of the patient's teeth to a model relationship determined by the orthodontist. This is true even though a considerable effort has been made, and a significant amount of money has been expended, to advance the state of the art in the last twenty years.
In co-pending application Ser. No. 07/467,162 filed by Craig A. Andreiko and Terry L. Sterrett on Jan. 19, 1990, for a "Method of Forming Orthodontic Brace and Orthodontic Brace Formed By Such Method", now U.S. Pat. No. 5,139,419 is disclosed for forming slots or grooves in brackets with individual parameters, and for disposing the brackets at individual positions on a patient's teeth, to obtain a disposition of an arch wire in the slots in the brackets in a progressively curved configuration in a plan view and a planar disposition in an elevational view. The slots are formed in the brackets, and the brackets are disposed on the patient's teeth, with the desired parameters by determining the mesio-distal profile (or thickness) of each tooth in the patient's mouth between the tip of the tooth and the gum.